Fuzzy control for temperature and humidity in refrigeration systems

Abstract

In this paper, improved control strategies for refrigeration systems based on fuzzy logic are discussed. For the development of these control concepts physical understanding of the process dynamics is needed. Therefore, a thermodynamic model is used to study the dynamic properties of the cold store, with emphasis on the coupling of temperature and relative humidity. With this knowledge, together with the heuristic knowledge of refrigeration engineers, rule-based control strategies for refrigeration systems are proposed. For the implementation the fuzzy logic method is used. The design with fuzzy logic allows one to take into account the complex coupling of the dynamic variables temperature and humidity in a straightforward manner. A survey of the control structure and simulation results are presented. It is shown that the fuzzy controller gives favourable process behaviour, e.g. under the influence of disturbances or after changes of set points.